Isolating gap electrode



Feb. 2, 1954 c. w. PETERSEN 2,668,210

ISOLATING GAP ELECTRODE Filed Nov. 30, 1950 'INVEN 47 A omvsv GL/FFORD w PETERSEN,

Patented Feb. 2, 1954 UNITED STATES PATENT @FFICE 2,668,210 Is'oLA'riNG GAP ELECTRODE Clifford W. Petersen, Wauwatosa, Wis, assignmto McGraw Electric Company, Milwaukee, Wis., a corporation of Delaware Application November 30, 195%), Serial No. 198,336

3 Claims. 1

This invention relates generally to electrical protective devices, and more specifically to the spark. gap electrodes which serve to normally electrically isolate surge arresting devices during period when surge conditions are not present.

Protective equipment for electrical apparatus has long been provided for arresting lightning and other surges, and also for overload current protection. Many attempts have been made to provide all-over protection ina unitary structure with varying degrees of commercial success. The present invention contemplates the use of independently functioning protective devices, including a surge arrester and a fuse cutout for overloadprotection. Bothdevices are preferably mounted on a single bracket in the proximity of one another and of the'equipment to be protected.

It is essential to provide a spark gap means for electrically isolating the arrester until such time that it is needed to dissipate line surges. For safety reasons, it is preferable to mount the; fuse cutout in such position that replacement of expended fuses may be performed from safeope'rating distances from hot lines or equipment which may endanger the operator.

To provide for a safe and convenient mounting of the fuse cutout-arrester combination, it often becomes necessary to reset spark gap electrodes for establishin predetermined gap dimensions. This adjustment was inconvenient to make after the equipment was mounted on pole cross-arms or transformer tanks, and often required modification of associated parts. It is contemplated by the present invention to provide a universal spark gap device which provides a constant gap dimension without subsequent adjustment and modification, no matter the mounting position of the various cooperating parts.

When such protective equipment is mounted directly on transformer brackets in conjunction with transformer primary bushings, it often is necessary to provide specially constructed fuse cutouts for each of various type transformers predetermined spark gap distance is retainedno' 2 matter the mounting position of the arrester or cutout with respect to the protected equipment.

Another object of this invention is to provide a spark gap electrode for electrical apparatus that is universally adaptable for any of many mounting positions of cooperating protective equipment.

These and other objects are effected by the invention as will be apparent in the following description and claims taken in connection withthe accompanying drawings, forming a part of this application, in which:

Figure l is a fragmentary side elevational view of a protected transformer including a surge arrester and fuse cutout combination employing the novel spark gap arrangement.

Figure 2 is a top plan View of the combined surge arrester and fuse cutout shown in Figure 1 provided for mounting directly on a transformer and employing the novel spark gap device.

Figure 3 is a fragmentary side elevational view showing the preferred manner of mounting the cooperating electrodes of the novel device on cooperating arrester and fuse cutout installations.

Figure 4 is a fragmentary side elevational view showing another embodiment of the novel device.

The novel protective device may be most advantageously disclosed as shown in Figures 1 and 2, for transformer mounting, wherein the transformer is denoted generally by the reference character T.-

The transformer is shown provided with a primary bushing 1 including an upper terminal 2. The fuse cutout includes a lower fuse contact spring 3, which is electrically connected to the bushing terminal 2 through a contact 4 and a solderless connector 5. The fuse link 6 is suspended between the contact spring 3 and the upper fuse contact arm 1 and engaging either of the slotted portions 8 or 9 of the contact arm 1, whichever is most convenient for mounting. A terminal it is provided on the upper contact arm for electrical connection with the line.

The upper fuse contact arm 1 is supported by the free end of fuse cutout insulator H, which is mounted on a hanger E2. The hanger l2 preferably comprises spaced parallel metal straps l3 and idformed to grippingly engage members supported therefrom. The supported insulator H is held in place with bolt and nut assemblies l5 protruding through openings in each of the parallel straps I3 and I4 which urge the straps toward one anotherto grippingly engage the supported members. A surge arrester l 6 is supported by the hanger assembly in substantially the same at manner as described above. For further support, additional straps l2a may be provided as shown in Figure l.

The hanger 12 may be conveniently supported by any conventional type transformer mounting brackets, the unit being universally adaptable no matter the position of the bracket, designated by reference character H, with relation to the bushing I.

The surge arrester I3 is preferably provided with a solderless connector ill for electrical connection with ground or neutral. It is usual practice to use an expulsion type arrester with this installation, but it is within the scope of this invention to provide any protective surge arresting device requiring an external spark gap.

The novel universally adaptable spark gap device Will hereinafter be described: A spark gap electrode [9 is affixed to the upper end of the arrester Hi. The electrode is held in adjustable engagement with the arrester by the nut and stud assembly 26 and elongated opening 2! clearly shown in Figure 2. The opposite spark gap electrode 22 is mounted on the insulator it and is electrically connected to the upper fuse con- #5 tact arm 7 by a bolt 23 which concurrently engages the lower portion of the contact arm '1 and 'a tapped hole in electrode 22.

The novel electrode 22 is provided with a portion 2 1 which has arcuate electrode surface 22a, i

which surface is preferably concentric with the axis of the insulator H. The portion 24 is integral with the attaching portion which is provided with a tapped hole to receive the bolt 23.

The electrode is provided with an elongated :13

differently with respect to the transformer mounting brackets on various types of transformers, the lower fuse contact spring positions would be varied accordingly. It will be obvious that no matter the position of the upper contact arm I with respect to the bushing i, the spark l gap distance 26 will remain constant between the electrode l9 and the arcuate portion 24 of electrode 22. This adaptability may be emphasized by the broken line portions in Figure 2 showing how the insulator l I may be rotated in the hanger l2 to change the position of the contact l with relation to the bushing I. The spark gap distance 26 remains constant no matter the change of position of the contact arm I.

The universality of the novel device will also permit the most advantageous positioning of the fuse contacts for convenience in re-fusing. Thus, a lineman may re-fuse from a safer position below or from the side of the transformer using an operating stick to replace the fuse link.

Thus, he need not reach over the top of the lead being electrically connected with the secondary ground or neutral lead.

It will be obvious that the novel external spark said fuse cutout each being supported in adjain Figures 1, 2 and 3.

gap device may be used in conjunction with any installations requiring universally mounted protective equipment, and may also be conveniently adapted for cross-arm mounting of this equipment.

A convenient cross-arm mounting arrangement is shown in Figure 4 Where the spark gap electrode 22 is positioned at the upper end of an insulator 30 in a manner substantially identical to that described with reference to Figures 1, 2 and 3. A line terminal BI and the upper fuse contact 32 may be fastened to the insulator alone with the electrode 22 by bolt 23. The fuse link 6 is here suspended between the contact 32 and the contact spring 33 in like manner as described with reference to Figures 1, 2 and 3. The contact spring 33 is supported by the lower end of insulator 30, which also has a terminal 34 attached thereto. The terminal 34 is adapted to electrically connect the fuse cutout with the protected equipment, i. e., transformer.

Both the fuse cutout and surge arrester it are positioned proximate to one another on the hanger 35 in substantially the same manner as described above. The cooperating gap electrode [9 is initially positioned on the upper end of the arrester 16 to provide a predetermined gap distance 26 with electrode 22. Electrical connection with ground or neutral is preferably made through the solderless connector [8 of arrester 16. The hanger 35 may be conveniently fastened to cross-arm 36 with bolt and nut assemblies 31 and backing plate 38, or with any of many wellknown mounting devices.

It will be apparent that the novel spark gap arrangement shown in Figure 4 will function with effectiveness equal to the embodiment disclosed The fuse cutout insulator 30 may be rotated to any desired position in the hanger without necessitating additional gap adjustments. Thus, the live portions of the protective equipment may be positioned at safe operating distances for re-fusing and other maintenanc operations.

It will be obvious that the gap electrodes l9 and 22 may be interchanged if so desired (not shown) without changing the inherent operating characteristics of the gap arrangement. It

will also be obvious that both electrodes of the spark gap may be of arcuate sectors should it be desired to rotatably mount both the arrester and fuse cutout (not shown) while maintaining a constant spark gap distance.

It will be apparent that a novel spark gap means for cooperating devices used in protection of electrical apparatus has been provided, and which means is universally adaptable for any of many mounting arrangements of companion protective equipment.

I claim:

1. In an electrical protective assembly includterminal and a fuse cutout having a terminal, the comb1nat1on of a pair of cooperating isolating gap electrode members, said surge arrester and cent spaced relationship by said support member,

w the axes of revolution of said arrester and said cutout being substantially parallel to one another, one of said electrode members being in electrical connection with and secured to the terminal of said arrester, the other of said electrode members being in electrical connection with and secured to the terminal of said cutout, said electrode members being positioned to lie in substantially a common plane, and one of said electrode members having an arcing surface in said plane substantially arcuate in contour and rotatable about one of said axes of revolution, whereby a predetermined spaced, fixed gap dimension is normally maintained between said electrode members.

2. In a protective device for electrical transformers including a primary transformer bushing having a terminal, a support member, a surge arrester having a terminal and a fuse cutout comprising two fuse contact members and an insulating member, the combination of a pair of cooperating isolating gap electrode members, said surge arrester and said insulating member each being supported in adjacent spaced relationship by said support member, one of said fuse contact members being in electrical connection with and secured to said primary bushing terminal, the axes of revolution of said arrester and said insulating member being substantially parallel to one another, one of said electrode members being in electrical connection with and secured to the terminal of said arrester, the other of said electrode members being in electrical connection with and secured to one of said fuse contact members, said electrode members being positioned to lie in substantially a common plane, and one of said electrode members having an arcing surface in said plane substantially arcuate in contour and rotatable about one of said axes of revolution, whereby a predetermined spaced, fixed gap dimension is normally maintained between said electrode members.

3. In an electrical protective assembly includ ing a surge arrester having a terminal and a fuse cutout having a terminal, the combination of a pair of cooperating isolating gap electrode members, said surge arrester and said fuse cutout each being supported in adjacent spaced relationship by said support member, the axes of revolution of said arrester and said cutout being substantially parallel to one another, the first of said electrode members being in electrical con nection with and secured to the terminal of said arrester, the second of said electrode members being in electrical connection with and secured to the terminal of said cutout, said electrode members being positioned to lie in substantially a common plane, and said second electrode member having an arcing surface in said plane substantially arcuate in contour and rotatable about the axis of revolution of said fuse cutout, whereby a predetermined spaced, fixed gap dimension is normally maintained between said electrode members.

CLIFFORD W. PETERSEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 496,308 Heinze Apr. 25, 1893 2,327,865 Brown et a1 Aug. 24, 1943 2,372,035 \Vade Mar. 20, 1945 2,519,289 Roman et a1 Aug. 15, 1950 2,549,853 Rorden Apr. 24, 1951 

